The primary objective will be to elucidate the interaction between environmental events (particularly social) and circulating levels of gonadal hormones. Specific manipulations of social situations will be used to influence aggressive and sexual experiences and individual social status. Radioimmunoassay techniques will be used to test for predicted changes in circulating levels of testosterone, progesterone, estradiol and other selected hormones. These measures will then be correlated both with immediate and long term behavioral changes in a search for feedback mechanisms relating hormones to behavior and the dissociation of behavior with immediate hormonal levels as a consequence of the long term influences of earlier hormonal and behavioral manipulations. The hormonal system is viewed as a regulatory mechanism adjusting an organism to future conditions based on experience in the immediate past. Experience in one behavioral realm may organize behavioral tendencies such as to influence multiple future behavioral potentials. Temporary reductions in competitiveness for vital resources and in reproductive activity, related to immediate previous experiences, may nonetheless serve to increase genetic fitness over an individual's reproductive lifespan.